How Many Ways Can Nature Kill the Goose That Laid the Golden Egg? – The Many Mechanisms of Evolved Glyphosate Resistance

Weeding has been the bane of humanity since the dawn of agriculture. For about 70 years, synthetic herbicides have removed much of the drudgery of this onerous task. Glyphosate was introduced as a non-selective herbicide in 1974. Its ideal properties made it a very popular herbicide, and the introduction of glyphosate-resistant (GR) crops allowed its use as a selective herbicide, greatly expanding its use to become the most used herbicide on earth. For farmers who used glyphosate in GR crops, it was the golden age of weed management, as this technology significantly improved the efficacy and reduced the cost of weed management. Weed management was also simplified, an asset that was particularly valuable to part-time farmers. Furthermore, this technology provided the environmental benefits (reduced soil loss and fossil fuel use) of significantly reducing tillage. Farmers saved billions of US$, and weed management became more effective and simple. Indeed, to many farmers, glyphosate with GR crops became the goose that laid the golden egg. After more than 20 years of use, the first cases of GR weeds were reported in the latter 1990s. After a lag period of less than 10 years after the first GR weed was reported, the number of species reported to have evolved glyphosate resistance began to increase in a linear fashion, reaching 53 species in 2021, third only to atrazine (66 species), a much older herbicide and to ALS inhibitors (168 species), which include several different herbicides used in numerous crops since the 1980s. The long lag phase before any resistance was detected led some to believe by the mid-1990s that evolution of resistance was improbable. By this time, glyphosate use was greatly increasing, especially in GR crops, an ideal situation for the evolution of resistance. After this, the number of glyphosate-resistance cases exploded, and the mechanisms of resistance to many of these cases of resistance were determined. A recent, short commentary detailed these mechanisms after a new mechanism of resistance was reported. The number of mechanisms for resistance to no other herbicide comes close to those of glyphosate. In the present paper, we briefly describe the many evolved mechanisms by which weeds have evolved resistance to glyphosate.

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ELECTRIC BUNTING TO MAINTAIN BODY TEMPERATURE DURING EXCHANGE TRANSFUSION IN THE NEWBORN INFANT

PEDIATRICS ◽

10.1542/peds.7.2.207 ◽

1951 ◽

Vol 7 (2) ◽

pp. 207-209

Author(s):

P. VOGEL ◽

R. E. ROSENFIELD ◽

M. STEINBERG

Keyword(s):

Body Temperature ◽

Exchange Transfusion ◽

Prolonged Exposure ◽

Newborn Infants ◽

Electric Heating ◽

Hot Water ◽

Maximum Temperature ◽

Ideal Situation ◽

The Many ◽

Water Proof

THE maintenance of proper body temperature has been a serious problem in the performance of exchange transfusions on newborn infants suffering from hemolytic disease. Many of these infants are in such poor condition that extreme care in their handling is required, including incubation, oxygen and tracheal aspiration. The many procedures necessary create the hazard of prolonged exposure to room temperature, and a number of deaths may have resulted directly or indirectly from hypothermia. In the Children's Hospital in Boston, the entire exchange transfusion is carried out with the infant lying in a Hess bed; this is an ideal situation which undoubtedly is not readily available in most institutions where an exchange transfusion must be performed. The maintenance of body temperature with electric heating pads and/or hot water bottles has proved cumbersome and unsatisfactory, and has resulted in a number of burns, particularly about the buttocks. A washable electric blanket bunting has been designed (see Figs. and 2) to maintain the temperature of newborn infants throughout the procedure of an exchange transfusion, as well as for a period following the procedure, if a heated crib is not available. This bunting was constructed by the General Electric Company using water-proof washable material and employing the principles of the commercial electric blanket. The bunting can be regulated to any desired temperature although the maximum temperature obtainable is 42°C., which avoids the possibility of skin burns. The design of the bunting is simple: it is a bag with a zipper along one side to allow for easy insertion and removal of the baby, and a "U" shaped zippered flap which can be opened to provide a window at the approximate position of the umbilical cord.

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PLANCTation

OpenPhysio Journal ◽

10.14426/opj/202111pp03 ◽

2021 ◽

Author(s):

Nora Amalie Karlsen ◽

Keyword(s):

Large Scale ◽

Healthcare Professionals ◽

Resistance To Change ◽

Global Environmental Change ◽

Female Leadership ◽

Environmental Benefits ◽

Oxygen Generation ◽

Health And Wellbeing ◽

Global Environmental ◽

The Many

‘PLANCTation’ – The story about Aurelia Oline Ebeltoft is a story about how the power and ingenuity of female leadership and large-scale collaboration can help find solutions to the health and existential problems created by severe global environmental change. With a focus on solving air-pollution and its consequences for people’s health and lung function, Aurelia’s invention of PLANCTation – an algae farm for oxygen generation – has given people and planet a new lease on life. Algae farming is, in fact, being increasingly explored for a variety of health and environmental benefits, so this story is incredibly close to some very real developments. Woven into, however, is also a sense of getting fed up with resistance to change and a call to take responsibility, as people and healthcare professionals. To recognize and open ourselves to the many different possibilities to contribute to people’s health and wellbeing and take action.

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New Case of False-Star-Grass (Chloris distichophylla) Population Evolving Glyphosate Resistance

Agronomy ◽

10.3390/agronomy10030377 ◽

2020 ◽

Vol 10 (3) ◽

pp. 377 ◽

Cited By ~ 2

Author(s):

José G. Vázquez-García ◽

Sajedeh Golmohammadzadeh ◽

Candelario Palma-Bautista ◽

Antonia M. Rojano-Delgado ◽

José A. Domínguez-Valenzuela ◽

...

Keyword(s):

Weed Management ◽

Chemical Control ◽

Shikimic Acid ◽

Dry Weight ◽

Glyphosate Resistance ◽

Integrated Weed Management ◽

Resistance Level ◽

Susceptible Population ◽

First Case

Chloris distichophylla, suspected of glyphosate resistance (GR), was collected from areas of soybean cultivation in Rio Grande do Sul, Brazil. A comparison was made with a susceptible population (GS) to evaluate the resistance level, mechanisms involved, and control alternatives. Glyphosate doses required to reduce the dry weight (GR50) or cause a mortality rate of 50% (LD50) were around 5.1–3 times greater in the GR population than in the GS population. The shikimic acid accumulation was around 6.2-fold greater in GS plants than in GR plants. No metabolized glyphosate was found in either GR or GS plants. Both populations did not differ in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) basal activity or in vitro inhibition of EPSPS activity by glyphosate (I50). The maximum glyphosate absorption was observed at 96 hours after treatment (HAT), which was twofold higher in the GS plants than in the GR plants. This confirms the first case of glyphosate resistance in C. distichophylla. In addition, at 96 HAT, the GS plants translocated more 14C-glyphosate than the GR ones. The best options for the chemical control of both C. distichophylla populations were clethodim, quizalofop, paraquat, glufosinate, tembotrione, diuron, and atrazine. The first case of glyphosate resistance in C. distichophylla was due to impaired uptake and translocation. Chemical control using multiple herbicides with different modes of action (MOA) could be a tool used for integrated weed management (IWM) programs.

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Target Site Resistance to Acetolactate Synthase Inhibitors in Diplotaxis erucoides and Erucaria hispanica–Mechanism of Resistance and Response to Alternative Herbicides

Agronomy ◽

10.3390/agronomy10040471 ◽

2020 ◽

Vol 10 (4) ◽

pp. 471 ◽

Cited By ~ 2

Author(s):

Maor Matzrafi ◽

Ofri Gerson ◽

Moshe Sibony ◽

Baruch Rubin

Keyword(s):

Management Strategies ◽

Acetolactate Synthase ◽

Poor Control ◽

First Case ◽

Evolution Of Resistance ◽

Target Site Resistance ◽

Excellent Control ◽

Diplotaxis Erucoides ◽

Als Inhibitors ◽

Two Populations

Diplotaxis erucoides and Erucaria hispanica are common weeds of the Mediterranean region; they infest various habitats including cultivated fields and roadsides. In several fields across Israel, farmers have reported on poor control of D. erucoides and E. hispanica plants using acetolactate synthase (ALS) inhibitors. Greenhouse experiments were conducted to determine the effect of various ALS inhibitors on plants from two potentially resistant D. erucoides and E. hispanica populations. Additionally, alternative management strategies using auxinic herbicides were studied. Plants from both populations exhibited resistance to all tested ALS inhibitors, up to 20-fold the label field rate, as compared with ALS sensitive populations of D. erucoides and E. hispanica. Sequencing of the ALS gene revealed Trp574 to Leu substitution in ALS-resistant D. erucoides plants, whereas a Pro197 to Ser substitution was detected in ALS-resistant E. hispanica plants. Although high levels of resistance were observed in individuals from both putative resistant populations, sensitive individuals were also detected, suggesting the evolution of resistance in these two populations is still in progress. Auxinic herbicides, 2,4-D, and mecoprop-P, provided excellent control of plants from both ALS-resistant populations. This study documents and confirms the first case of evolution of resistance to ALS inhibitors in D. erucoides and E. hispanica populations.

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Diverse Approaches to Herbicide-Resistant Weed Management

Weed Science ◽

10.1614/ws-d-15-00117.1 ◽

2016 ◽

Vol 64 (SP1) ◽

pp. 570-584 ◽

Cited By ~ 44

Author(s):

Micheal D. K. Owen

Keyword(s):

Weed Management ◽

Crop Production ◽

Production Systems ◽

Cost Effective ◽

Developed Countries ◽

Weed Species ◽

Herbicide Resistant ◽

Cost Effective Method ◽

Evolution Of Resistance ◽

Complexity Cost

Herbicides have been the principal means of weed control in developed countries for approximately 50 yr because they are the most cost-effective method. Such general use of herbicides has resulted in weed resistance to herbicides, which continues to be a growing problem. Within the past decade, the evolution of resistance to the once-dominant herbicide glyphosate has resulted in major concerns about the future ability to control weeds in many crop systems. Moreover, many weed species have evolved resistance to multiple mechanisms of herbicide action. Given the dearth of new herbicides with novel mechanisms of action, it appears inevitable that weed management programs will need to be supplemented by the use of tactics other than herbicides. However, the inclusion of more diversity for weed management also introduces complexity, cost, and time constraints to current crop production systems. This paper describes broadly the considerations, opportunities, and constraints of diverse weed management tactics to address the burgeoning problems with herbicide resistance.

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Modeling the Evolution of Glyphosate Resistance in Barnyardgrass (Echinochloa crus-galli) in Cotton-Based Production Systems of the Midsouthern United States

Weed Technology ◽

10.1614/wt-d-13-00013.1 ◽

2013 ◽

Vol 27 (3) ◽

pp. 475-487 ◽

Cited By ~ 19

Author(s):

Muthukumar V. Bagavathiannan ◽

Jason K. Norsworthy ◽

Kenneth L. Smith ◽

Paul Neve

Keyword(s):

United States ◽

Weed Management ◽

Production Systems ◽

Relative Effectiveness ◽

Glyphosate Resistance ◽

Case Scenario ◽

Management Options ◽

Worst Case ◽

Resistance Evolution ◽

Initial Frequency

Glyphosate-resistant (GR) weeds have been a prime challenge to the sustainability of GR cotton-based production systems of the midsouthern United States. Barnyardgrass is known to be a high-risk species for evolving herbicide resistance, and a simulation model was developed for understanding the likelihood of glyphosate resistance evolution in this species in cotton-based systems. Under a worst-case scenario of five glyphosate applications in monoculture GR cotton, the model predicts resistance evolution in about 9 yr of continuous glyphosate use, with about 47% risk by year 15. A unique insight from this model is that management in response to GR Palmer amaranth in this system (a reactive response) provided a proactive means to greatly reduce the risks of glyphosate resistance evolution in barnyardgrass. Subsequent model analysis revealed that the risk of resistance is high in fields characterized by high barnyardgrass seedbank levels, seedling emergence, and seed production per square meter, whereas the risk is low in fields with high levels of postdispersal seed loss and annual seedbank loss. The initial frequency of resistance alleles was a high determinant of resistance evolution (e.g., 47% risk at year 15 at an initial frequency of 5e−8vs. 4% risk at 5e−10). Monte Carlo simulations were performed to understand the influence of various glyphosate use patterns and production practices in reducing the rate and risk of glyphosate resistance evolution in barnyardgrass. Early planting and interrow cultivation are useful tools. Crop rotation is effective, but the diversity of weed management options practiced in the rotational crop is more important. Diversifying weed management options is the key, yet application timing and the choice of management option is critical. Model analyses illustrate the relative effectiveness of a number of diversified glyphosate use strategies in preventing resistance evolution and preserving the long-term utility of glyphosate in midsouthern U.S. cotton-based production systems.

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Resistance to Bensulfuron-Methyl in Water Plantain (Alisma plantago-aquatica) Populations from Chilean Paddy Fields

Weed Technology ◽

10.1614/wt-08-078.1 ◽

2008 ◽

Vol 22 (4) ◽

pp. 602-608 ◽

Cited By ~ 2

Author(s):

Rodrigo Figueroa ◽

Marlene Gebauer ◽

Albert Fischer ◽

Marcelo Kogan

Keyword(s):

Weed Management ◽

Wide Spectrum ◽

Acetolactate Synthase ◽

Rice Fields ◽

Integrated Weed Management ◽

Cross Resistance ◽

Content Type ◽

Als Inhibitors

Bensulfuron-methyl (BSM) has been one of the most widely used herbicides in Chilean rice fields because it controls a wide spectrum of weeds and does not require field drainage for application. However, failures of BSM to control water plantain in rice fields have been noted since 2002. We assessed BSM effects on suspected resistant (CU1 and CU2) and susceptible (AN1) water plantain accessions collected in Chilean rice fields during 2004 and 2005. BSM rates resulting in 50% growth reduction (GR50) of CU2 and CU1 plants were 12- and 33-fold higher than for AN1 plants, respectively. Acetolactate synthase (ALS) activity assays in vitro suggested resistance in CU1 and CU2 was due to an ALS enzyme with reduced BSM sensitivity compared to the AN1 biotype. Resistance indices (RI), or ratios of the resistant to susceptibleI50values (BSM rate to inhibit ALS-enzyme activity by 50%), were 266 (CU2/AN1) and > 38,462 (CU1/AN1). This agreed with in vivo ALS activity assays whereRIwere 224 (CU2/AN1) and > 8,533 (CU1/AN1). Resistance levels detected in whole-plant or in vivo ALS activity assays were orders of magnitude lower than those detected in in vitro ALS activity studies suggesting nontarget site mechanisms may have mitigated BSM toxicity. However, a consistent ranking of BSM sensitivity levels (AN1 > CU2 > CU1) throughout all three types of assays suggests resistance is primarily endowed by low target site sensitivity. We conclude that susceptible and resistant water plantain biotypes coexist in Chilean paddies, and the use of integrated weed management involving herbicides with a different mode of action would be imperative to prevent further evolution of resistance to BSM and possibly cross-resistance to other ALS inhibitors. In vitro ALS-enzyme assays provided the best discrimination of resistance levels between biotypes.

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Modeling Glyphosate Resistance Management Strategies for Palmer Amaranth (Amaranthus palmeri) in Cotton

Weed Technology ◽

10.1614/wt-d-10-00171.1 ◽

2011 ◽

Vol 25 (3) ◽

pp. 335-343 ◽

Cited By ~ 52

Author(s):

Paul Neve ◽

Jason K. Norsworthy ◽

Kenneth L. Smith ◽

Ian A. Zelaya

Keyword(s):

Weed Management ◽

Management Strategies ◽

Resistance Management ◽

Glyphosate Resistance ◽

Palmer Amaranth ◽

Case Scenario ◽

Management Options ◽

Worst Case ◽

Resistance Risk ◽

Resistance Evolution

A simulation model is used to explore management options to mitigate risks of glyphosate resistance evolution in Palmer amaranth in glyphosate-resistant cotton in the southern United States. Our first analysis compares risks of glyphosate resistance evolution for seven weed-management strategies in continuous glyphosate-resistant cotton monoculture. In the “worst-case scenario” with five applications of glyphosate each year and no other herbicides applied, evolution of glyphosate resistance was predicted in 74% of simulated populations. In other strategies, glyphosate was applied with various combinations of preplant, PRE, and POST residual herbicides. The most effective strategy included four glyphosate applications with a preplant fomesafen application, and POST tank mixtures of glyphosate plusS-metolachlor followed by glyphosate plus flumioxazin. This strategy reduced the resistance risk to 12% of populations. A second series of simulations compared strategies where glyphosate-resistant cotton was grown in one-to-one rotations with corn or cotton with other herbicide resistance traits. In general, crop rotation reduced risks of resistance by approximately 50% and delayed the evolution of resistance by 2 to 3 yr. These analyses demonstrate that risks of glyphosate resistance evolution in Palmer amaranth can be reduced by reducing glyphosate use within and among years, controlling populations with diverse herbicide modes of action, and ensuring that population size is kept low. However, no strategy completely eliminated the risk of glyphosate resistance.

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Effectiveness of Herbicides for Control of Hairy Vetch (Vicia villosa) in Winter Wheat

Weed Technology ◽

10.1614/wt-d-14-00139.1 ◽

2015 ◽

Vol 29 (3) ◽

pp. 509-518 ◽

Cited By ~ 11

Author(s):

William S. Curran ◽

John M. Wallace ◽

Steven Mirsky ◽

Benjamin Crockett

Keyword(s):

Winter Wheat ◽

Weed Management ◽

Acetolactate Synthase ◽

Oxidase Inhibitor ◽

Management Program ◽

Integrated Weed Management ◽

Hairy Vetch ◽

Synthetic Auxins ◽

Als Inhibitors ◽

Tribenuron Methyl

A field experiment was conducted in 2009–2010 at Pennsylvania and Maryland locations, and repeated it in 2010–2011 to test the effectiveness of POST-applied herbicides at fall and spring timings on seeded hairy vetch in winter wheat. A total of 16 herbicide treatment combinations was tested that included synthetic auxins, acetolactate synthase (ALS) inhibitors, and a protoporphyrinogen oxidase inhibitor. Spring applications tended to be more effective than fall applications. Among synthetic auxins, clopyralid (105 g ae ha−1) and treatments containing dicamba (140 g ae ha−1) were effective at both timings, resulting in greater than 90% hairy vetch control at wheat harvest. Pyroxsulam and prosulfuron applied at 18 g ai ha−1 provided the most effective hairy vetch control (> 90%) at both application timings among ALS inhibitors. Spring applications of several herbicides provided moderate (> 80%) to high (> 90%) levels of hairy vetch control, including: 2,4-D amine (140 g ae ha−1), mesosulfuron-methyl (15 g ai ha−1), tribenuron-methyl (13 g ai ha−1), and thifensulfuron/tribenuron-methyl treatments (16 and 32 g ai ha−1). Winter wheat injury was evaluated, but symptoms were negligible for most treatments. Winter wheat yields declined with increasing hairy vetch biomass. Fall herbicides may be prioritized to reduce hairy vetch competition during the fall and early spring growing season. Our research has established that several synthetic auxin and ALS-inhibiting herbicides, applied POST in fall or spring, can be safely used in winter wheat to control hairy vetch in an integrated weed management program.

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Modeling the Simultaneous Evolution of Resistance to ALS- and ACCase-Inhibiting Herbicides in Barnyardgrass (Echinochloa crus-galli) in Clearfield®Rice

Weed Technology ◽

10.1614/wt-d-13-00106.1 ◽

2014 ◽

Vol 28 (1) ◽

pp. 89-103 ◽

Cited By ~ 16

Author(s):

Muthukumar V. Bagavathiannan ◽

Jason K. Norsworthy ◽

Kenneth L. Smith ◽

Paul Neve

Keyword(s):

Weed Management ◽

Key Management ◽

Production Systems ◽

Acetolactate Synthase ◽

Rice Production ◽

Management Scenarios ◽

Management Options ◽

Evolution Of Resistance ◽

Clearfield Rice ◽

Simultaneous Evolution

Herbicide-resistant barnyardgrass has become widespread in the rice production systems of the midsouthern United States, leaving few effective herbicide options for controlling this weed. The acetolactate synthase (ALS)- and acetyl-CoA carboxylase (ACCase)-inhibiting herbicides remain largely effective in Clearfield®rice production, but strategies need to be developed to protect the long-term utility of these options. A two-trait model was developed to understand simultaneous evolution of resistance in barnyardgrass to the ALS- and ACCase-inhibiting herbicides in Clearfield rice. The model was used to predict resistance under a number of common weed management scenarios across 1,000 hypothetical rice fields in the Mississippi Delta region and answer some key management questions. Under an ALS inhibitor–only program consisting of three annual applications of imidazolinone herbicides (imazethapyr or imazamox) in continuous Clearfield rice, resistance was predicted within 4 yr with 80% risk by year 30. Weed management programs that consisted of ALS- and ACCase-inhibiting herbicides such as fenoxaprop and cyhalofop greatly reduced the risk of ALS-inhibiting herbicide resistance (12% risk by year 30), but there was a considerable risk for ACCase resistance (evolving by year 14 with 13% risk by year 30) and multiple resistance (evolving by year 16 with 11% risk by year 30) to both of these mechanisms of action. A unique insight was that failure to stop using a herbicide soon after resistance evolution can accelerate resistance to the subsequent herbicide option. Further, a strong emphasis on minimizing seedbank size is vital for any successful weed management strategy. Results also demonstrated that diversifying management options is not just adequate, but diversity combined with timely herbicide applications aimed at achieving high efficacy levels possible is imperative.

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